John Blanksby

The management of sediment in combined sewers

Abstract Sediments in sewers are ubiquitous because of the diverse nature of the inputs. Over the past decade or so, new understanding of the provenance, behaviour and nature of sewer solids is now allowing more effective means for solids management. Whilst current computer models are good at representing the hydraulic performance of sewer systems, their handling of sewer solids and associated processes is still embryonic. Hence any attempts to manage in-sewer solids more effectively require a diversity of approaches, both for any modelling studies and for the selection of the most appropriate option. Little information currently exists on which to draw to determine cost-effective or wholelife solutions. Nonetheless significant advances have been made in enhancing the traditional approaches to sewer solids management which have been in use for more than a century.

A review of the UK approach to measuring the performance of combined sewer overflows

Two current research projects have recently investigated post-project appraisal and flow measurement at combined sewer overflows. The paper sets out the context in which these projects were carried out and specifically identifies the current performance measures and measurement procedures used within the United Kingdom.

Determination of sewer roughness and sediment properties using acoustic techniques.

Measurements have been carried out to determine the effect of porous sediments in a pipe on the attenuation and spectrum of the airborne acoustic field. The results show that the presence of even a relatively thin sandy layer results in a considerable increase in the acoustic attenuation over the broad frequency range. The measured value of the relative attenuation is in the range of 0.8 dB/m. The effect of the sediment on the acoustic spectrum is the reduction in energy of the propagating modes, which is an easily detectable phenomenon. These results pave the way for the development of the instrumentation for non-invasive characterisation of the parameters of sediments in wastewater systems.

The Determination of Sewer Roughness and Sediment Properties Using Acoustic Techniques

Measurements have been carried out to determine the effect of porous sediments in a pipe on the attenuation and spectrum of the airborne acoustic field. The results show that the presence of even a relatively thin sandy layer results in a considerable increase in the acoustic attenuation over the broad frequency range. The measured value of the relative attenuation is in the range of 0.6 dB/m. The effect of the sediment on the acoustic spectrum is the reduction in energy of the propagating modes, which is an easily detectable phenomenon. These results pave the way for the development of the instrumentation for non-invasive characterisation of the parameters of sediments in wastewater systems.